Book excerpt: This volume aims to document the authors' prescription for the architecture, the way the component services are fitted together to provide collaborative tools for video, audio and shared workspaces. The authors have decided to take a new approach to the field by using a prescriptive rather than descriptive style. The text is aimed at technical readers such as developers, undergraduate or postgraduate (MSc) courses on multimedia and networking, and professionals. The subjects covered include the network requirements, the media encoding techniques including basic compression techniques, the protocols (rtp/rtcp, rsvp etc.), the distributed algorithms for synchronization, reliability, security and so on.